need reassurance pls 😭 help

im so annoyed and in tears after my ob visit, two weeks ago i was here and when they measured my stomach it was measuring on time for 30 weeks, i went back today at 32w3d and they had a student doctor do it and said it was measuring behind at 29cm. she took so long to find the heartbeat and had me scared almost in tears. my ob came in and said she wants to do a growth scan tomorrow now im about to be stressing and crying til they can tell me everything is alright.